The present invention relates to an optical detection device.
The optical detection of components in fluids is well known in the art. Chemical separation techniques such as liquid chromatography are generally followed by further separation or detection steps. Measuring of concentrations of interesting components being enriched in an elute, e.g. may be detected by application of techniques applying physical phenomena that don't interfere with the chemical fluidic system and which don't disturb the “shape” of the component's concentration peak. If chemical separation is performed in a cylindrical chromatography column one might wish to proceed using a cylinder shaped detection device in order to prevent disturbing of the “plug-shape” of the separated components. Optical detection for measuring physical properties such as concentrations accordingly goes perfect together with the before mentioned requirements.
In order to perform such optical detection, an optical detection device generally comprises a measuring chamber or cuvette containing the fluid to be analyzed, a light emitting and a light receiving device. One may perform transmission measurements by guiding light through the fluid and measuring the light throughput, under consideration of optical laws such as Beer's law, which is known to those skilled in the art. Generally one can say that the reliability on optical measurement is based on the precision of controlling and detecting the light input into the fluid, its throughput and its output—parameters that depend on the characteristic such as surface design or length of the measuring chamber or cuvette, respectively.
In U.S. Pat. No. 6,281,975, Munk describes a capillary flow cell with protruding bulb ends providing a high light throughput entrance window for the cell, aiming for an improved sample illumination.
UK 2,193,313 A to Lefebre and Schirmer refers to a spectral analysis apparatus and method for measuring the spectral absorbance of fluid samples, focusing on the adjustment of the light path through the sample to optimize the amount of light absorbed by the sample, intending to enable absorbance measurements over a wide range of absorptivities and concentrations.
EP 0,089,157 to Le Febre discloses an optical detector cell for determining the presence of a solute in a sample fluid, for the particular application in miniature chromatographic and micro spectroscopic applications. An optical flow path which is parallel to the fluid flow path is provided, allowing maximizing of the sample corresponding to a fixed sample volume, whereby the ability results to measure low threshold concentrations in solutes.
U.S. Pat. No. 4,477,186 to Carlson refers to a photometric cuvette for optical analysis of through flowing media, designed for the measurement of minimum sample amounts.